The Kaimingjie germ weapon attack was a Japanese biological warfare bacterial germ strike against Kaimingjie, an area of the port of Ningbo in the Chinese province of Zhejiang in October 1940, during the Second Sino-Japanese War. These attacks were a joint Unit 731 and Unit 1644 endeavour. Bubonic plague was the area of greatest interest to the doctors of the units mentioned above. Six different plague attacks were conducted in China during the war, between the start of aggression and the end of the war.